
an electron microscopic study of developing gall
bladder epithelium in the rabbit
the gall bladder epithelium of the
adult rabbit consists of two types of cells.
the first and more common type shows features associated with absorption,
notably microvilli, limited pinocytosis, some lysosomes and an elaboration of
the lateral cell membrane and intercellular spaces.  the mitochondria are
concentrated in a subapical band.
the second and more infrequent type is a dark rod-shaped cell of unknown
function but which may be a dehydrated epithelial cell.
foetal epithelial cells lack the functional adult characteristics; the mito-
chondria are uniformly distributed.  in addition they display basal granules
and apical apocrine bullae.
epithelial cell damage and white cell infiltration occurs between 24 days
after birth or just after.
just before birth some epithelial cells are very large and pale with smooth
outlines, others are more dense and display vigorous pinocytosis.
adult characteristics are acquired at or immediately after birth and pino-
cytosis subsides.  it is believed that water resorption occurs before the
functional changes which allow continuous passage of water into the
circulation.
